A two-year prospective follow-up of 29 (100%) children and adolescents with disruptive behavior disorders found that baseline lumbar CSF monoamine metabolite concentration and autonomic nervous system reactivity had significant predictive value (Kruesi et al, 1992). 5-HIAA concentration significantly predicted severity of physical aggression during follow-up. Skin conductance level significantly predicted institutionalization. CSF HVA predicted suicide attempts. The direction was as predicted, with lower CSF 5-HIAA and lower autonomic activity correlated with poor outcome. Moreover, when hierarchically entered into multiple regression and discriminant function analyses after a variety of other non-laboratory predictors, CSF and autonomic measures still contributed significantly to the variance. Preliminary studies of stimulant drug response of patients with Hyperactivity and Tourette's disorder indicates that not only do some patients' tics not worsen on stimulants, but that over time and/or increase in dose, tics may even improve.